As of November 24, 2009

for international journal X-Ray Spectrometry (John Wiley & Sons Ltd.)

Kβ/Kα intensity ratio in Cr, Fe and Ni (November 10, 2009)

Dr. I. Han (Ağrı İbrahim Çeçen University, Turkey) and his colleagues have published a paper on the relationship between the Kβ/Kα X-ray fluorescence intensity ratio and valence-electron configurations.  For more information, see the paper, "Valence-electron configuration of Fe, Cr, and Ni in binary and ternary alloys from Kβ-to-Kα X-ray intensity ratios", I. Han et al., Phys. Rev. A80, 052503 (2009).

X-ray reflectivity analysis of self assembled nano patterns (November 9, 2009)

Foamlike, cellular structures of the monolayer of organic capped nanoparticles can sometimes be observed on liquid surfaces.  Professor M. K. Sanyal (Saha Institute of Nuclear Physics, India) and his lab members studied the time evolution in the structure and morphology of transferred monolayers of gold-thiol nanoparticles, formed at the air-water interface at different surface pressure, on to a silicon surface.  The research group employed two complementary techniques, X-ray reflectivity and atomic force microscopy (AFM), to see the whole drying-mediated self-assembly of nanoparticles.  For more information, see the paper, "Nanopattern formation in self-assembled monolayers of thiol-capped Au nanocrystals", R. Banerjee et al., Phys. Rev. E80, 056204 (2009).

Soft and hard X-ray diffraction microscopy of frozen biological specimens (November 5, 2009)

So far, X-ray microscopy with many types of lens has achieved great success in the observation of biological cells.  In order to extend the limits of spatial resolution and efficiency, X-ray diffraction microscopy (also called coherent X-ray diffraction imaging), which uses coherent X-rays and some image reconstruction algorithms instead of an optical lens system, is now considered as a promising procedure to see whole cells at once and pick out much smaller features, down to around 10 nm or even less.  A research group led by Professor C. Jacobsen (Stony Brook University, USA) recently reported the results for yeast cells with 520 eV soft X-rays at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory, USA.  Dr. A. Madsen (European Synchrotron Radiation Facility (ESRF), Grenoble, France) and his colleagues observed the cells of the bacteria D. radioduran with 8 keV X-rays.  The advantage of using hard X-rays is the ease of sample handling, and the validity of thin sample approximation for future 3D reconstructions through phasing a diffraction volume.  In both cases, a rapid freezing technique (instead of previously used freeze-drying) was used to avoid the effects of radiation damage from synchrotron X-ray photons.  The Stony Brook group plunged cells in their natural wet state into liquid ethane and maintained them at below -170 ^oC, leading to the reduction of artifacts due to damage from dehydration, ice crystallization, and radiation.  In the ESRF setup, as absorption in air of 8 keV X rays is small, a nonvacuum environment was implemented for ease of sample handling.  Similar to the system for macromolecular crystallography applications, they based the samples in a continuous cryogenic nitrogen gas jet at around -165 ^oC.  The spatial resolution was 25 nm and 30-50 nm, for soft and hard X-rays cases, respectively.  For more information, see the papers, "Soft X-ray diffraction microscopy of a frozen hydrated yeast cell", X. Huang et al., Phys. Rev. Lett., 103, 198101 (2009), and "Cryogenic X-ray diffraction microscopy for biological samples", E. Lima et al., Phys. Rev. Lett., 103, 198102 (2009)
 

Direct observation of BaTiO₃ polarization clusters by soft X-ray laser (November 5, 2009)

Nanometer scale dipole moments in the polarization clusters in BaTiO₃ are believed to be thermally excited and thermally relaxed within a picosecond time scale. However, so far, there have been no reports on the direct observation of the dynamics of these dipole moments in such a very short time scale.  The limitation here is mainly due to the low spatial coherence of the X-ray beam, in particular when synchrotron radiation is used as a light source.  Professor K. Namikawa (Tokyo Gakugei Univ, Japan) and his colleagues have recently obtained some interesting results.  To measure the time correlation of speckle intensities, they employed a soft X-ray pulse laser (7 ps in pulse width, 3.5×10¹⁰ photons/sec/pulse, 13.9 nm in wavelength, band width 10^-4, angular spread 0.5 mrad) at Japan Atomic Energy Agency, Kizugawa, Japan, and a Michelson-type delay pulse generator as well as an X-ray streak camera.  Spatial coherence in their system was estimated at more than 90 %.  The evolution of the relaxation time of the dipole moment near the Curie temperature (TC) was studied.  It was found that the maximum relaxation time (~90 ps) appears at a temperature of 4.5 K above the TC, being coincident with the one where the maximum polarization takes place.  For more information, see the paper, "Direct observation of the critical relaxation of polarization clusters in BaTiO₃ using a pulsed X-ray laser technique", K. Namikawa et al., Phys. Rev. Lett., 103, 197401 (2009).
 

A method for evaluating the spatial coherence of an X-ray beam (November 5, 2009)

Professors T. Narayanan (ESRF, Grenoble, France), M. Giglio (XFEL, Hamburg, Germany) and their collaborators have recently published an interesting paper on a novel method to map the two-dimensional transverse coherence of an X-ray beam.  The technique uses the dynamical near-field speckles formed by scattering from colloidal particles, which are executing Brownian motions.  It is possible to measure the change of the interference fringes, and consequently the fluctuation of speckles.  It was found that the coherence properties of synchrotron radiation from an undulator source are obtained with high accuracy.  For more information, see the paper, "Probing the transverse coherence of an undulator X-ray beam using Brownian particles", M. D. Alaimo et al., Phys. Rev. Lett., 103, 194805 (2009).
 

High resolution Ti Kβ" and Kβ_2,5 spectra in PIXE (October 30, 2009)

One of the most important applications of X-ray spectroscopy is chemical state analysis.  A research group led by Dr. M. Jaksic (Rudjer Boskovic Institute, Croatia) has recently reported chemical effects observed in high resolution Kβ spectra of Ti oxides and other compounds in the case of 2 MeV proton excitation.  In addition to the determination of the oxidation number by the energy differences between Kβ_1,3 and Kβ₅, the sum of the relative intensities of Kβ_2,5 and Kβ" can give information on the length of chemical bonds.  The influence of self-absorption for thick samples on X-ray spectra is also discussed.  For more information, see the paper, "Chemical effects on the Kβ" and Kβ_2,5 X-ray lines of titanium and its compounds", L. Mandic et al., Phys. Rev. A80, 042519 (2009).  Readers might be also interested in the recent synchrotron radiation studies on Ti oxides and other compounds reported by Dr. B. Beckoff’s group (PTB, Germany), "Evaluation of high-resolution X-ray absorption and emission spectroscopy for the chemical speciation of binary titanium compounds", F. Reinhardt et al., Anal. Chem. 81, 1770 (2009).
 

Novel X-ray phase-difference microscopy based on Talbot effects (October 28, 2009)

X-ray absorption microscopy is simple, but has low sensitivity in biological samples that are made of light elements.  X-ray phase contrast imaging can provide contrast that is 3 orders of magnitude greater than X-ray absorption.  However, phase contrast imaging has not been that widely used so far mainly because of the unusual requirements of the experimental setup.  Dr. W. Yashiro (The University of Tokyo, Japan) and his colleagues have recently proposed a novel setup that is feasible.  The research group simply added a transmission grating to the setup for conventional X-ray absorption microscopy with a Fresnel Zone Plate (FZP) objective lens.  Because of the self-imaging phenomenon in Talbot effects, a phase difference image can be produced by the transmission grating placed at the downstream of the back focus of the FZP.  The experiment was done at beamline BL20XU, SPring-8.  For more information, see the paper, "Hard-X-Ray Phase-Difference Microscopy Using a Fresnel Zone Plate and a Transmission Grating", W. Yashiro et al., Phys. Rev. Lett. 103, 180801 (2009).
 

Table-top soft X-ray undulator source (September 27, 2009)

Some readers might remember the news article, "A compact synchrotron light source driven by pulse laser", in X-ray Spectrometry, Vol. 37, No.2 (2008).  The essential point is that a table top pulse laser can be used as an alternative to a linear or circular electron accelerator.  The article above reported the first successful synchrotron radiation generation from laser-plasma-accelerated electrons, but the wavelength was only in the visible to infrared region.  Recently, an international team led by Professors S. Karsch and F. Grunera achieved a new breakthrough.  The team belongs to Munich’s Cluster of Excellence “Munich Centre for Advanced Photonics” (MAP), in the Laboratory for Attosecond Physics (LAP) of Ludwig-Maximilians-Universitat (LMU) in Munich and the Max Planck Institute of Quantum Optics (MPQ) in Garching.  In their experiment, the electron accelerator is driven by pulses from a 20 TW (850 mJ in 37 fs) laser system.  Focused into a hydrogen-filled gas cell with a length of 15 mm, the laser pulses produce stable electron beams showing a quasi-monoenergetic energy spectrum with a stable peak in the range of 200-220 MeV and 7 pC of charge in the whole spectrum.  In order to transport the electron beam from the plasma accelerator, the scientists employed a pair of miniature permanent-magnet quadrupole lenses, which have been found to be critical for stability.  The spectrum of their 30cm-long undulator typically consists of a main peak at a wavelength of 18 nm (fundamental), a second peak near 9 nm (second harmonic) and a high-energy cutoff at 7 nm.  For more information, see the paper, "Laser-driven soft-X-ray undulator source", M. Fuchs et al., Nature Physics. 5, 826 (2009).
 

Large chemical shift in Eu Lγ emission spectra (January 26, 2009)

Eu is one of the most interesting lanthanides, compounds of which often exhibit remarkable optical, electrical, and magnetic properties.  Therefore, it is extremely important to develop a technique for chemical state analysis.  The X-ray emission spectra of Eu had not been thought to exhibit significant chemical effects.  A research group led by Professor H. Hayashi (Japan Women’s Univ) firstly found a large chemical shift (~5 eV) in Eu Lγ₄ emission line, depending on the valence state.  They discussed the feasibility of using this as a probe for spin- and valence-selective X-ray absorption fine structure spectroscopy.  For more information, see the paper, "Probe for spin- and valence-selective X-ray absorption fine structure spectroscopy: EuLγ₄ emission", H. Hayashi et al., Anal. Chem., 81, 1522 (2009).
 

The 4^th Asada award and the special award 2009 (November 5, 2009)

The recipient of the 4th Asada Award, which is presented in memory of the late Professor Ei-ichi Asada (1924-2005) to promising young scientists in X-ray analysis fields in Japan, is Dr. Akiko Hokura (Tokyo Denki Univ., "Study on accumulation of heavy metals in phytoremediation plant by synchrotron radiation micro XRF imaging and XAFS analysis").  From this year, the Discussion Group of X-ray Analysis, the Japan Society for Analytical Chemistry decided to establish the special award to recognize scientists who exhibit outstanding achievement and make a substantial contribution to the advancement of the X-ray analysis field.  The recipient of the special award 2009 is Dr. Toshio Shiraiwa, who contributed greatly in the early days of X-ray absorption spectroscopy by means of his short-range order theory ("The theory of the fine structure of the X-ray absorption spectrum", J. Phys. Soc. Jpn. 13, 847 (1958)) and also provided the basis of the fundamental parameter method in X-ray fluorescence by Fujino-Shiraiwa’s formula ("Theoretical calculation of fluorescent X-ray intensities in fluorescent X-ray spectrochemical analysis", Jpn. J. Appl. Phys. 5, 886 (1966))  The ceremony was held during the 45th Annual Conference on X-Ray Chemical Analysis, Japan, at Osaka City University, Osaka.
 

X-rays named top innovation by Science Museum London (November 4, 2009)

The discovery of X-rays was named the most important modern scientific achievement in a poll conducted for the Science Museum London, beating the Apollo spacecraft and DNA.  Nearly 50,000 members of the public voted in the museum or online.  The emblem of the London museum's centenary is now an X-ray machine.  For further information, visit the museum’s Web page, http://www.sciencemuseum.org.uk/
 

Nature News on the recent status of X-ray free electron lasers in Stanford and Hamburg (October 7, 2009)

A recent edition of Nature News featured the international race to build X-ray free electron laser facilities. At the Linac Coherent Light Source (LCLS), Stanford, USA, scientists have succeeded in lasing 8 keV X-rays and started to use them in their research since April, this year (2009).  Meanwhile, soft X-ray laser FLASH, which is a pilot facility for XFEL at the European X-Ray Free-Electron Laser (XFEL), Hamburg, Germany, has been open for scientific use since 2005, and the main XFEL will be completed in 2014.  Nature News interviewed various people both in Stanford (Joachim Stohr, Jerome Hastings and John Bozek) and Hamburg (Heinz Graafsma, Helmut Dosch and Massimo Altarelli).  For more information, see the article, "X-ray free-electron lasers fire up", Eric Hand, Nature 461, 708-709 (2009).
 

Solar Metrology launches line-mountable XRF tool for CIGS (November 18, 2009)

Solar Metrology (Hollbrook, NY, USA) has expanded its SMX XRF tool portfolio for film composition and thickness measurement of copper indium gallium diselenide (CIGS) photovoltaic deposition.  For further information, visit the web page, http://www.solarmetrology.com/
 

Thermo Scientific’s ARL OPTIM’X cement analyzer (November 11, 2009)

Thermo Fisher Scientific Inc. has announced the introduction of a new analytical package ARL OPTIM'X, designed specifically for the X-ray analysis of cement-related materials.  For further information, visit the web page, http://www.thermo.com/
 

Amptek’s new 129 eV energy-resolution Si drift detector (October 1, 2009)

Amptek Inc., has unveiled a new advanced Si drift detector (SDD).  The new detector uses a sensor with an effective area size of 25 mm², while energy resolution and the peak to background ratio are 129 eV (FWHM at 5.9 keV) and 8000:1, respectively.  This compares with 7 mm² and 136 eV for its previous product, the XR100-SDD.  For further information, visit the web page, http://www.amptek.com/

SpectroscopyNow.com

For additional news about X-ray analysis and other spectroscopy sciences, browse the Wiley website.

Kenji Sakurai
Director, X-Ray Physics Group, National Institute for
Materials Science (NIMS)
and Professor, Doctoral Program in Materials Science and
Engineering, Graduate School of Pure and Applied Sciences,
 University of Tsukuba
1-2-1, Sengen, Tsukuba, Ibaraki 305-0047 Japan
Phone : +81-29-859-2821, Fax : +81-29-859-2801
sakurai@yuhgiri.nims.go.jp
http://www.nims.go.jp/xray/lab/